On-line Monitoring Of Partial Discharge In 10kV High-voltage Switchgear Based On UHF

High voltage switchgear is a very important power distribution equipment in power system.10 k V high voltage switchgear is the most direct power supply to the user.In the long-term operation,the High-voltage switchgear will appear the phenomenon of insulation deterioration,and thus lead to partial discharge(PD);and for the power distribution equipment,partial discharge is one of the leading causes of power equipment insulation aging or deterioration,which fuelled the equipment damage and power system accidents;And the loss of the accident is not only the economic losses,serious or even lead to personal safety accidents,and the social influence is incalculable.Therefore,the on-line monitoring of the high-voltage switchgear in the operation can provide important parameters and basis for the condition maintenance of switchgear,which has a high value of research and application,such as it can improve the quality of power supply,reduce the probability of the accident and control the loss to a minimum.Ultra-high frequency(UHF)as the detection method of partial discharge detection technology developed rapidly in recent years,with the high frequency response,high sensitivity and strong anti-interference advantages,which can meet the requirements of detecting partial discharge in high-voltage switchgear well.Based on the 10 k V indoor metal armoured mobile type high-voltage switchgear as the research object,a set of partial discharge monitoring system based on UHF is developed,and a series of researches are carried out around it.First,in order to verify the correctness of on-line monitoring system,partial discharge defect model must be set up.Targeting at the typical insulated defects in high-voltage switchgear,the finite element analysis model of the tip discharge,the inner air-gap discharge and the suspended potential discharge are built.Through the electric field analysis of model,we can get the corona onset voltage,breakdown voltage and corona layer thickness of each model,and under thesame voltage level,study the discharge characteristics of each model vary with the main design parameters,besides,under the same design parameters,study the discharge characteristics of each model vary with the variation of applied voltage.On this basis,the defects of the partial discharge models are developed,and the effectiveness of partial discharge defect model is verified by high-voltage test.And then,using SolidWorks to model 1: 1 high voltage switchgear and using XFDTD to analyze the influence of the waveform parameters of the discharge source and the monitoring distance on the partial discharge UHF signal propagation in the switchgear.On this base,through the simulation analysis to determine the optimal installation position of the UHF sensor,it provide theoretical guidance for the high voltage test,which improved the performance of the monitoring system.Furthermore,based on the partial discharge statistical characteristic parameters extracted by wavelet packet,the pattern recognition model of partial discharge of high voltage switchgear based on SVM has built.MPGA was used to optimize the parameters of SVM,the text recognition algorithm of the pattern recognition model into the monitoring system.Based on the above research,this paper through the UHF sensor,signal conditioning unit,high speed data acquisition unit and PC developed a high-voltage switchgear partial discharge UHF monitoring system.Finally,the test platform is built and the test scheme is designed to test the core functions of the monitoring system.The experimental results shows that the partial discharge monitoring system has a good ability of monitoring and pattern recognition.